Paraffin alkylation process using a hydrogen fluoride-silver fluoride catalyst solution



United States Patent O 3,080.439 PARAFHN ALKYLATION PROCESS USING A HY- 'DROGEN FLUORlDE-SILVER FLUORIDE CATA- LYST SOLUTION David A. McCauley, Homewood, Ill., assigner to Standard Oil Company, Chicago, Ill., a corporation of ludiana Filed .lune 23, i961, Ser. No. 119,224 11 Claims. (Cl. 26h-683.51)

This invention relates to the alkylation of isoparans and olefns using a modified hydrogen fluoride catalyst.

Pa-raiin alkylation processes using a hydrogen fluoride catalyst have been used for some years in the petroleum industry. These processes do not produce an alkylate with as high an octane number as the industry would like; also these processes produce too large a portion of the alkylate boiling outside of the C8 range; and these processes produce too much of the low octane Css. ln an attempt to overcome these problems, the industry has investigated HF catalyst using modifiers.

One object of this invention is to produce a higher octane paraffin alkylate using an HF catalyst. Another object is to decrease the portion of the alkylate falling outside the C8 range when using an HF catalyst. Still another object is to increase the high octane Cs of the C3 portion of the alkylate when using an HF catalyst. Other objects of this invention will become evident during the detailed description of the invention.

The annexed FIGURE which forms a part of this specification sets out one illustrative embodiment of the process of the invention.

lt has been discovered that the `above objects are obtained when a liquid hydrogen fluoride catalyst is moditied by the addition of the hereinafter described amounts of silver fluoride. This modified catalyst is used in an alkylation process in which isoparaflins having 4-5 carbon atoms and oletins having 3-5 carbon atoms are reacted together at a temperature on the order of 30l30 F. The reactants charged to the reacto-r in the process of the invention are isoparaifins having 45 carbon atoms and olefms having 3-5 car-bon atoms. Illustrative compounds are isobuftane, isopentane, propylene, butene-l, butene-Z, isobutylene and pentene-l. The hydrocarbon feed to the process may contain in addition to the defined isoparatiins and olens, inert hydrocarbons such as nbutane and n-pentane. The process can utilize a mixture of isoparafiins and/ or a mixture of olefins. Particularly suitable is a refinery butano-butylene stream; this stream contains n-butane, isobutane and the C4 oleiins isomers and may contain some C3 and C5 hydrocarbons. Sulfur compounds in the feed react with the silver uoride, and therefore, it is preferred to remove any sulfur compounds from the feed ybefore charging the feed to the process.

The isoparafins and olefins are present in the reaction Zone in the mole ratio of isoparafrln to oleiins of at least 2. Preferably, this ratio is higher and may be 100 land even more. Ratios in the order of 1,000 may be obtained by multi-point olefin injection. It is preferred that the ratio used be about 4-l0.

The catalyst used in the process is liquid substantially anhydrous hydrogen fluoride. The substantially anhydrous hydrogen fluoride may contain as much as 3% water. It is preferred to operate with anhydrous hydrogen fluoride containing 1% or less water.

The hydrogen fluoride catalyst is modified by the presence of dissolved silver fluoride. rl`he catalyst solution contains about 2-15 parts by weight of silver fluoride per l() parts by Weight of hydrogen fluoride. The amount of silver fluoride present in the catalyst solution has an influence on the octane number of the alkylate product; higher octane numbers are obtained when using silver ICC 2 Ifluoride in an amount of about 5-l2 parts by weight per l0() parts by weight of hydrogen fluoride. When operating with isobutane and 4 carbon olefins as the feed to the process, it is preferred that silver fluoride Ibe present in an amount of about 9 parts by weight per 100 parts by weight of hydrogen fluoride.

The catalyst solution and the hydrocarbon feed are present in the reaction zone in a volume ratio of at least 0.6-in other words, at least 6 parts of catalyst solution per l0 parts of feed. Usually more catalyst solution is used and preferably a volume ratio of about 1-3 is present in the reaction zone.

The process is carried out using liquid feed and liquid catalyst. The process is carried out under sumcient pressure to keep the feed and the catalyst in the liquid state.

The hydrocarbon feed and catalyst solution must be contacted together in the reaction zone to obtain the `desired alkylate product. This contacting may be obtained by any one of the procedures known to those skilled in this art.

The Aalkylation reaction is carried out at a temperature of about 30-l30 F. The reaction can be carried out at slightly higher temperatures and slightly lower temeratures. lt has lbeen observed that this reaction is not temperature sensitive with respect to octane number of the product. Therefore, ordinary ambient temperatures on the order of 60'80 F. may be used.

The reactants are contacted with the catalyst solution in the reaction zone for la time sufficient to obtain an alkylate product. It is preferred that this time -be such to substantially convert all of the olefin to alkylate.

A mixture of hydrocarbons and catalyst solution is removed from the reactor. This mixture is composed of a liquid hydrocarbon phase and a liquid catalyst solution phase. The liquid hydrocarbon phase contains alkylate product and unreacted feed hydrocarbons. Separation of the liquid hydrocarbon phase from the liquid catalyst solution phase may be obtained by gravity separation or other means known to those skilled in this art.

The alkylate product is recovered from the hydrocarbon phase using distillation or other methods known to those skilled in this art.

One illustrative embodiment of this invention is described in connection with the figure. It is to be understood that the figure is schematic in nature and does not contain many items of equipment such as pumps and valves because these items can be supplied by those skilled in this art.

The feed to this embodiment of the invention is a refinery B-B stream containing no C3 or C5 hydrocarbons. The B-B feed is supplied from source 11 and passed by way of line f3 to feed drier 15. The drying operation is necessary to the control of the water content of the B-B stream in order to avoid dilution of the HF catalyst. The feed drying operation may be any conventional procedure but in this instance the feed drier is a conventional bauxite operation. The dried feed is passed by way of line ll7 and line 19 to reactor 2l. Recycle isobutane is also introduced to reactor 2l by Away of lines 23 and 19.

Reactor 2l hereunder shown as a vertical contacting vessel is provided with an agitator (not shown) driven by motor Z5 and internal heat exchanger 27. The alkylation reaction is exotherniic and in order to control temperature within the reactor cooling water is passed by way of line 29 through heat exchanger 27 and withdrawn by way of line 3l. The reactor effluent comprising catalyst solution, alkylate product and unreacted hydrocarbons is withdrawn by way of line 33 and passed to settler 35.

The catalyst solution is introduced to reactor 21 by way of line 37. The catalyst solution in line 37 comprises liquid HF catalyst with dissolved silver fluoride and some red oil. In general the red oil in the catalyst solution assenso will be from l4%. Typically the red oil will 'be 2% or less of the catalyst solution. ln this embodiment the red oil is controlled to about 1%.

In this embodiment the conditions within reactor Z1 are as follows: the ratio of isobutane to C.; olens about 6; the ratio of catalyst solution to hydrocarbon feed about 1.5; the silver liuoride content of the catalyst solution about 9 parts by weight per l0() parts of hydrogen fluoride; tne water content of the hydrogen fluoride catalyst about 0.5; the temperature of the reactor contents about 80 F.

The contents of settler separate into an upper liquid hydrocarbon phase containing the alkylate product and a lower catalyst solution phase. The liquid hydrocarbon phase contains dissolved HF and usually some oecluded catalyst phase material. The liquid catalyst phase solution is withdrawn from settler 35 by way of line 39. Most of the catalyst solution is passed by way of line 37 back to reactor 21. The remainder is passed by way of line 41 to HF column 43 where the regeneration of HF-AgF catalyst solution is begun.

The upper hydrocarbon phase is removed by way of line 45 and passed to column L37. Column Li7 has within it reboiler 48. The overhead from column 4.7 is passed by way of line 49, condenser 5l, line 53 to reilux drum 55. The overhead stream is composed of a mixture or" HF and hydrocarbons. Then in reflux drum this mixture separates into an upper hydrocarbon phase and a low'er HF phase. rthe upper hydrocarbon phase is returned to column 47 by way of line S7 to act as a reflux stream. The lower HF phase is Withdrawn from rellux drum 55 by way of line 59 and returned to reactor 21 by way of lines 61 and 37. y

The bottoms from column i7 are withdrawn by way of line 63 and passed to treater 65. This stream contains dissolved iiuorine compounds which have to be removed in order to obtain the desired alkylate product quality. Procedures for removing the iluorine compounds are known to those skilled in this art. ln this instance bauxite treater 65 is used for the removal.

The defluorinated stream from bauxite treater 65 is passed by way of line o7 to deisobutanizer tower 69, which is provided with reboiler 71. The overhead from tower o9 which is composed of propane and lighter hydrocarbons and isobutane is passed by way of line 73 to depropanizer tower 75 which is provided with reboiler 77. The bottoms stream from tower 69 is withdrawn and passed by way of line 79 to debutanizer tower 81 which is provided with reboiler S3.

Propane and lighter hydrocarbons are with rawn overhead from depropanizer tower '75 by way of line 35 and removed from the process. lsobutane is withdrawn from the bottom of tower 75 by way of line 2.3 and returned as a recycle stream through line 19 to reactor 21.

Normal butano is withdrawn overhead from debutanizer tower 81 by way of line 37 and removed from the process. Alkylate product is withdrawn from the bottom of debutanizer tower Sil and passed by way of line 89 to bauxite treater 91. ln order to be certain that all of the fluorine compounds in the alkylate product are removed bauxite treater 91 is provided. Bauxite treater 91 operates in the same manner and for the same purpose as bauxite treater 65.

The del'luorinated alkylate product is withdrawn from bauxite treater 91 by way of line 93 and passed to alkylate fractiouator 95 which is provided with reboiler 98. Methods of separating the Cs in the alkylate product are known. In this embodiment the C5-C7 fraction in the alkylate product is withdrawn overhead from fractionator 95 by way of line 97. The C8 fraction of the alkylate product is withdrawn by Way of line 99 and the C9 plus fraction is withdrawn from the bottom of fractionator 9S by way of line 1M.

The regeneration of the HF catalyst solution is begun in column 43 which is provided with reboiler 1G33. Sufd ncient HF is removed from the contents of column e3 by way of overhead line 1&5 to obtain a concentrated solution of AgiE and red oil in HF. The HF removed by line 16525 is passed to storage drum 1157. The concentrated solution is removed from column d3 by way of valved line 169 and passed to mixer 111.

rl`he red oil content of the catalyst solution is controlled by using a hydrocarbon solvent to dissolve the red oil in the concentrated solution in mixer 111. The solvent is a hydrocarbon boiling above HF. The solvent acts to dissolve the red oil and to remove it from the 3HE-Agli solution. Heavy alkylate hydrocarbons are particularly suitable for use as the solvent. The quantity ot solvent used to dissolve the red oil is dependent somewhat on the temperature oi operation and on the oil content of the catalyst solution to be returned to reactor 21.

The solvent is passed from source 113 by way of valved line 115 and line 117 to mixer 111 and dissolves the red oil in the concentrated solution. The mixture of solvent and concentrated solution is withdrawn from mixer 111 by way of valved line 119 to recovery vessel 121 which is constructed of an upper zone and lower zone 125. internal reboiler 127 is in upper zone 123 and internal reboiler 129 is in lower zone 125. Most of the HF in the mixture of solvent and concentrated solution is removed by way of overhead valved line 131 and passed to storage drum ll'. Zones 123 and 125 are separated by perforated plate 123. The bottoms from zone 123 which are composed of red oil, solvent AgF and some HF are passed through perforated plate 15:3 into Zone The remaining HF is removed as a vapor through plate 128 to zone 123. The solvent and dissolved red oil are decanted from the Agi2 and removed from zone 125 by way of valved line 133, and line 13S. The bottoms from Zone 125 which are a slurry of AgF and solvent are removed by way of valved line 137 and passed to mixer 139. Liquid HF is introduced into mixer 139 from storage drum ltr' by way of valved line 141 and dissolves the Agi2 in the slurry. The mixture of solvent and HF-AgF solution is removed from mixer 139 by way of line 143 and passed to settler 145 and separates into an upper solvent phase and a lower HF-AgF solution phase. The solvent phase is removed by valved line 147. This solvent stream may be reused and is then passed by way of valved line 149 to line 117 and mixer 111. However it is preferred to discard this solvent stream and it is then passed by way of valved line 151 and removed from the process by way of line 135. The lower HF-AgF solution is removed from settler by way of valved line 153 and passed by way of lines @S1 and 37 to reactor 21. Make up AgF to replace that lost 1n the process is passed from source 155 by way of tl'l'ed line 157 to the HF-AgF solution in valved line EXAMPLES The beneficial effect on octane number of the alkylate product by the addition of silver fluoride to the HF catalyst is shown by the data listed in Table l below. Runs 2, 3, and 4 are illustrative of the invention. Run 1 shows typical results using HF catalyst in Aan alkylation process. In each of these runs the alkylation reaction was carried out in a one liter Hastelloy autoclave having a cooling jacket and 1100 rpm. propeller stirrer. In each run, 250 grams of isobutane which was 99 percent pure was charged to the autoclave. ln addition 25() grams of liquid hydrogen iluoride, which was 99.6 percent pure and the remainder Water, was charged to the reactor. In runs 2, 3, and 4 silver lluoride which was CP grade was charged to the autoclave. Run l used no silver liuoride in order to illustrate the results with only hydrogen iluoride as the catalyst.

rlhe temperature of the autoclave was brought to 77 F. Agitation of the contents of the autoclave was started using the stirrer. Olen was then introduced into the intermingled contents of the autoclave at the rate of one ml. per minute, until the desired amount of olen had been charged to the autoclave. Upon completion of the addition of the olefin the agitation of the contents was stopped and the contents allowed to settle from lll-l5 minutes. Throughout the runs, suflicient pressure was used to keep the hydrocarbons and HP liquid.

A liquid hydrocarbon phase and a liquid HF-AgF were separately withdrawn from the autoclave. The hydrocarbon phase was washed with caustic to remove entrained HF and then washed with water to remove any remaining caustic in the hydrocarbons. The C5-C8 fraction of the alkylate product was analyzed using gas chromatography. The Cg-ifraction of the alkylate product was obtained using distillation. The CFR-R (ASTM research) octane number of the clear C5-C8 fraction of the alkylate product was obtained using the Micro-Method.

Table I Run No 1 2 3 4 Temperature, F 77 77 77 77 Feed:

Isobutane, g 250 250 250 25() Butene-2, ml 70 70 70 f 0 Butene-l, m1 0 0 0 60 H ,g 250 250 2 250 W t. percent; AgF on HF 4. 8 10.0 10. 0 Alkylate Product (C5-C8):

Percent (J5-C1 6.3 3.5 3. 4 4.7 Percent O5- Trimethylpentanes 79. 7 83. 2 88. 0 77. O Dimethylhexancs. 13. 9 13. 2 8. 7 18. 3 Percent Ca in Alkylate 93. 6 96. 4 96. 7 95. 3 Tot 99.9 99.9 100. l 100.0 Percent 09+ in total allrylate 4. Il 3.1 Octane No., CFR-R Clear (C5-Csproduct). 96. 0 97. 8 99. 3 95.0

The results of Runs l through 4 are listed in the annexed Table I.

As can be seen from Table l, the octane number of the C-Cg fraction of the alkylate product was increased with the addition of AgF to the HF catalyst, in the cornparable runs l, 2, and 3. Butene-Z was used as the olen feed in runs l, 2, and 3.

The octane number of run 4 which used butene-l as the olefin feed was lower than that of run 1 which used butene-Z as the olen feed. It is known that HF alone under these conditions produces lower octane number alkylate from butene-l than from butene-Z; even with butene-l feed the modified catalyst gives a higher octane number than HF alone.

'Thus having described the invention what is claimed is:

l. A paraffin alkylation process which comprises: contacting a liquid feed hydrocarbon comprising isoparaflins having 4-5 carbon atoms and olelins having 3-5 carbon atoms, said isoparaflins and said -oleiins being present in a mole ratio of isoparafns to olens of at least 2, with a liquid substantially anhydrous hydrogen fluoride catalyst containing dissolved silver fluoride in an amount of about 2-15 parts by weight per 100 parts by weight of said hydrogen fluoride, said catalyst solution and said feed being present in a volume ratio of at least 0.6, said contacting being carried out at a temperature on the order of Sty-130 F., and said contacting continuing for a time sutcient to obtain an alkylate product.

2. The process of claim 1 wherein said isoparain is isobutane.

3. The process of claim tene-2.

4. The process of claim 1 wherein said feed hydrocarbon is a refinery butane-butylene stream.

5. The process of claim l wherein said silver fluoride is present in an amount of about 5-12 parts b-y weight per 100 parts by weight of said hydrogen uoride catalyst.

6. The process of claim 1 wherein said ratio of catalyst solution to said feed hydrocarbon is about l-3.

7. The process of claim 1 wherein said temperature is in the order of 60-80 F.

8. A process for producing paraffin alkylate which process comprises: =(l) contacting in the liquid state a hydrocarbon feed comprising isoparafns having from 4 to 5 carbon atoms and olens having from 3 to 5 carbon atoms, said isoparains being present in a mole ratio to said olelins of at least 2, in the presence of a liquid substantially anhydrous hydrogen uoride catalyst containing dissolved silver fluoride in an amount of about from 2 parts -to 15 parts by weight per 100 parts by weight of said hydrogen liuoride, said catalyst solution and said feed being present in a volume ratio ofat least 6 parts of said catalyst per l0 parts of said feed, said contacting being carried out at a temperature of about 3G130 F. and for a sufcient time to obtain an alkylate product; and (2) separating a hydrocarbon phase including said alkylate product from a catalyst phase.

9. A parailin alkylation process which comprises: (1). contacting a liquid feed hydrocarbon comprising iso butane and olefins containing 4 carbon atoms, said isobutane and said olelins being present in an external mole ratio of isoparafns to olelins of about 4-10, with a liquid substantially anhydrous hydrogen uoride catalyst containing dissolved silver fluoride in an amount of about 5-12 par-ts by weight per 100 parts by weight of said hydrogen fluoride, said catalyst solution and said feed being present in a volrune ratio of about l-3, said contacting being carried out at a temperature on the order of -80 F. and for a time to substantially convert all of Ithe olen to alkylate; (2) separating a liquid hydrocarbon phase containing alkylate product from a liquid catalyst phase; and (3) recovering said alkylate product from said hydrocarbon phase.

l0. The process of claim 9 wherein said silver liuoride is present in .an amount of about 9 parts by weight per parts by weight of said hydrogen lluoride.

lil. The process of .claim 9 wherein lsaid olein is butene-Z.

l wherein said olefin is bu- No references cited. 

1. A PARAFFIN ALKYLATION PROCESS WHICH COMPRISES: CONTACTING A LIQUID FEED HYDROCARBON COMPRISING ISOPARAFFINS HAVING 4-5 CARBON ATOMS AND OLEFINS HAVING 3-5 CARBON ATOMS, SAID ISOPARAFFINS AND SAID OLEFINS BEING PRESENT IN A MOLE RATIO OF ISOPARAFFINS TO OLEFINS OF AT LEAST 2, WITH A LIQUID SUBSTANTIALLY ANHYDROUS HYDROGEN FLUORIDE CATALYST CONTAINING DISSOLVED SILVER FLUORIDE IN AN AMOUNT OF ABOUT 2-15 PARTS BY WEIGHT PER 100 PARTS BY WEIGHT OF SAID HYDROGEN FLUORIDE, SAID CATALYST SOLUTION AND SAID 